This is the fifth biannual Gordon Research Conference on Mammalian DNA Repair, and alternates with the Gordon Conference on Mutagenesis. It will be held in Ventura, CA, in early February of 1995. This conference aims to address in a single meeting the diverse research areas crucial to determining the molecular mechanisms involved in repair of DNA in mammalian cells and the biological consequences of incomplete and/or inaccurate repair. This topic is of particular importance in assessment of the risk associated with exposure to environmental mutagenic and carcinogenic hazards, and is also of much interest to other disparate areas such as the variations among individuals in the efficacy of chemotherapeutic agents, theories of aging, evolutionary divergence of biochemical processes, and mapping/cloning human genes which modify response to exposures. The conference provides the opportunity for the interaction, in an informal setting, of a group of scientists who often do not find themselves at the same meeting. Discussions between the participants are likely to lead to an exchange of ideas, techniques, and approaches which will benefit many different research projects and areas. This meeting will include nine sessions covering a range of areas in which progress is being made rapidly and will feature talks by leaders in the fields aimed not only at scientists in the immediate area but those in related disciplines. The sessions will cover structures of DNA lesions and DNA packaging in chromatin, damage-inducible responses, repair heterogeneity in chromatin, proteins with-dual roles in repair and transCription, repair enzymology/pathways (e.g., neucleotide excision repair and mismatch repair), human repair deficient disorders and transgenic animal models. Support is requested towards the travel and conference fees for key participants from the U.S. and overseas, especially young investigators, who otherwise would not be able to attend. The need to support foreign participants, in part, is particularly important to preserve an international contribution which has been very valuable in past conferences, and because the field of DNA repair involves many major participants in European and Asian countries.